Dedicated to pursuing accuracy with an the 357 Magnum Revolver and 357 Lever Rifle. The most accurate ammo possible is developed with the surprising results published right here.

Friday, February 18, 2011

357 Magnum Accuracy is About Semi-Wadcutters. Overview of Most Accurate Moulds.

Review the most accurate load chart just below, and it's glaring that semi-wadcutters (SWC) are at the top. (Note the 358-429 is a Keith and a SWC.) Testing has included round nose, flat nose and wadcutter designs as well. Calling out moulds that aren't the most accurate isn't the goal here, so there won't be a long list of what hasn't worked very well. But, there are many.

Absence from the most accurate list means; they aren't that accurate or haven't been tested yet. Not when shot from a rest at 25 yards, and multiple 5 shot groups measured with calipers. Anyone can claim they shot off-hand (two handed & unsupported grip) and the gun shot better than they could, with any bullet. Of course it does. Remove the shooter from the equation as much as is afford-ably possible and run multiple tests, measure the groups with calipers and sort them. That's the only way to correctly determine which moulds and bullet designs are the most accurate.

The list I maintain is the very top of the tested-measured-sorted list, the most accurate cast bullets for your 357 magnum.

Various "max bullet in the chamber" designs as well as the standard flat nose, and various wadcutters have all been through the wringer. There may be a few new designs that test well, but they would be big shock at this point.

Two big surprises are:

Wadcutters aren't as accurate as SWC's

Lighter bullets such as the 140, 145 and some 150 grain versions don't do all that well. These are usually touted as the most accurate of all 357 bullets, but haven't proven it

The Lyman 358-477 design at 150 grains is an exception and groups less than 1 inch

Two big learning points are:

SWC's ranging from 158 grains to 200 grains are generally the most accurate, those and the Lyman 477 comprise 100% of the groups less than 1 inch

Keith style/design bullets do very well, but note that other SWC's are also on the list too, see pictures below

Note: It's really the length of the bullets that is important, longer bullets weight more which is why the weight and length are related. The length / diameter ratio has a lot to do with the accuracy. While this isn't the only factor about bullet design that is important, it is one important and often overlooked factor.

Looking at the results, it's obvious that longer bullets are more accurate. Also, a SWC is typically longer than a flat-nose of the same weight. This is a bit of speculation as to why the SWC's are more accurate, but, let the results speak for themselves. Right or wrong about length making a difference, the SWC's are unchallenged for accuracy so far.

The three bullets below from left to right are: 360-200-SWC (200 grain SWC from a NOE mould), 358-429 (168 grain Keith is from a NOE mould, it has a shorter nose than the Lyman and may fit your gun better. The longer Lyman design won't work in every 357, you have to test any 358-429 in your revolver or crimp it into the front driving band). These are the top 2 accurate bullets I load and shoot. The third bullet in the picture is from an very old Lyman 357-446 mould that drops a 162 grain SWC. It's undergoing testing now. Some others have reported excellent accuracy, others reported accuracy issues. It's interesting to look closely at the three, as they are all very similar:

Here's a closer look at the 200 SWC, the best group I've every shot are with this bullet (by .01 inch):

A closer look that the 358-429 168 grain Keith which is also super accurate, and virtually in a tie with the 200 SWC. Just .01 inch at 25 yards separates them, and that is splitting hairs:

The other mould that groups less than 1 inch at 25 yards is a Lee 358-158-TL, which I don't have a photo of. Here is the drawing from the Lee site. It's very similar to the other SWC's except for the lube grooves. If you don't mind tumble lubing, many folks like how easy it is, this is incredibly accurate and very inexpensive. A six cavity mould creates a large pile of bullets quickly too.

The current mould/bullet in test is the old Lyman 357446, here's a closer look the bullet it produces:

All the pictures expand when you click on them. Take a close look. I really like the big squared lube groove of a Keith style SWC. However the Lee is very different and is incredibly accurate as well.

If you are striving for the most accurate bullet/load in your 357 magnum a SWC from 158 to 200 grains is for you. If you can buy these particular moulds, they are proven (pending results of the 446). If you have one that looks very similar, you can use the "most accurate loads" and be close. Then work up the perfect load for your revolver. The specific design of the 358-477 is also a proven accurate bullet too. Other designs in this size/weight haven't worked as well.

The Accurate Load chart will be updated soon. It was to include early results with a new-to-me Dan Wesson with a 6 inch barrel. The groove size of the Taurus is .357 while the Dan Wesson is a huge .3588. The DW isn't liking the stiffer charges with fast powder. The Taurus 66 6 inch has proven to be more accurate than any other 357 revolver I've shot. Mine has .358 throats and at .357 groove, perfect for cast shooting. Some other makes have optimized for jacketed to the point of affecting accuracy of cast bullets.

If you are in the market and want a very accurate 357, consider getting a long barrel Taurus. Forget what everyone says about the other brands being better guns. Get the Taurus and out-shoot them.

Just for fun here's a handful of the 168 grain Keith's, including the nasty looking one with the rounded base: